Anode Reset Voltage Compensation for Variable Refresh Rate Flicker
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Solution Overview
Problem
Light emitting display apparatuses driven at a variable refresh rate experience luminance changes due to hysteresis of the driving transistor, leading to flickers, especially at low frequencies.
Innovation Solution
A light emitting display apparatus with an anode reset voltage applied to the gate of the driving transistor during the anode reset period being higher than the initial voltage input during the refresh period, and the use of a compensation gate pulse and compensation voltage to maintain luminance consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a light emitting display apparatus is driven at a variable refresh rate, then the refresh rate can be adjusted to match content requirements, but luminance changes occur due to hysteresis of the driving transistor causing flickers
Solution Approach 1:
The patent applies preliminary action by resetting the anode voltage to a predetermined voltage level during the anode reset period before the next refresh period begins. This preliminary reset action prevents hysteresis accumulation that would otherwise cause luminance instability and flickers during variable refresh rate operation, thereby maintaining reliable luminance output while allowing refresh rate adjustments.
2Reliability
If the anode reset voltage is increased to compensate for hysteresis, then luminance stability improves, but the voltage level exceeds the initial gate voltage
Solution Approach 1:
The patent implements periodic action by applying the anode reset voltage only during specific anode reset periods that occur between refresh periods, rather than continuously. This periodic application of higher voltage during designated reset intervals compensates for hysteresis effects and maintains luminance stability without requiring continuous high voltage, thereby simplifying overall voltage control while improving reliability.
Data Source
AI summary
A light emitting display apparatus includes a pixel driving circuit including a driving transistor and an anode reset capacitor connected to a gate of the driving transistor and a light emitting device configured to emit light with a current supplied through the driving transistor. An anode reset period, where a data voltage is not supplied to the driving transistor, is between refresh periods where the light emitting device emits the light with the data voltage supplied to the driving transistor, and an anode reset voltage supplied to the anode reset capacitor in the refresh period is higher than an initial voltage which is input to the gate of the driving transistor in the refresh period.